Technical Note
BA00DD0WCP-V5,BA00DD0WHFP,BA00DD0WT,
BA00CC0WT,BA00CC0WT-V5,BA00CC0WCP-V5,BA00CC0WFP
7/9
www.rohm.com
2011.03 - Rev.C
2011 ROHM Co., Ltd. All rights reserved.
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Vo Terminal
Please attach an anti-oscillation capacitor between VOUT and GND. The capacitance of the capacitor may significantly
change due to factors such as temperature changes, which may cause oscillations. Please use a tantalum capacitor or
aluminum electrolytic capacitor with favorable characteristics and small external series resistance (ESR) even at low
temperatures. The output oscillates regardless of whether the ESR is large or small. Please use the IC within the stable
operating region while referring to the ESR characteristics reference data shown in Figs.33 through 35. In cases where there
are sudden load fluctuations, the a large capacitor is recommended.
Fig.33:Output equivalent circuit
Fig.34:Io vs. ESR characteristics
Fig.35: Io vs. ESR characteristics
(BA□□CC0)
(BA□□DD0)
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Other
1) Protection Circuits
Overcurrent Protection Circuit
A built-in overcurrent protection circuit corresponding to the current capacity prevents the destruction of the IC when there
are load shorts. This protection circuit is a “7”-shaped current control circuit that is designed such that the current is
restricted and does not latch even when a large current momentarily flows through the system with a high-capacitance
capacitor. However, while this protection circuit is effective for the prevention of destruction due to unexpected accidents, it
is not suitable for continuous operation or transient use. Please be aware when creating thermal designs that the overcurrent
protection circuit has negative current capacity characteristics with regard to temperature (Refer to Figs.4 and 16).
Thermal Shutdown Circuit (Thermal Protection)
This system has a built-in temperature protection circuit for the purpose of protecting the IC from thermal damage. As
shown above, this must be used within the range of acceptable loss, but if the acceptable loss happens to be continuously
exceeded, the chip temperature Tj increases, causing the temperature protection circuit to operate.
When the thermal shutdown circuit operates, the operation of the circuit is suspended. The circuit resumes operation
immediately after the chip temperature Tj decreases, so the output repeats the ON and OFF states (Please refer to
Figs.12 and 24 for the temperatures at which the temperature protection circuit operates).
There are cases in which the IC is destroyed due to thermal runaway when it is left in the overloaded state. Be sure to
avoid leaving the IC in the overloaded state.
Reverse Current
In order to prevent the destruction of the IC when a reverse current flows through the IC, it is recommended that a diode
be placed between the Vcc and Vo and a pathway be created so that the current can escape (Refer to Fig.36).
2) This IC is bipolar IC that has a P-board (substrate) and P+ isolation layer
between each devise, as shown in Fig.37. A P-N junction is formed between
this P-layer and the N-layer of each device, and the P-N junction operates as a
parasitic diode when the electric potential relationship is GND> Terminal A,
GND> Terminal B, while it operates as a parasitic transistor when the electric
potential relationship is Terminal B GND> Terminal A. Parasitic devices are
intrinsic to the IC. The operation of parasitic devices induces mutual
interference between circuits, causing malfunctions and eventually the
destruction of the IC itself. It is necessary to be careful not to use the IC in ways
that would cause parasitic elements to operate. For example, applying a
voltage that is lower than the GND (P-board) to the input terminal.
Fig. 37: Example of the basic structure of a bipolar IC
22μF
OUT
IC
C(ADJ)
200
400
800
1000
0.1
1
10
Stable operating region
100
0
600
Unstable operating region
1
0.1
1
10
100
10
100
1000
OUTPUT CURRENT:lo(mA)
Unstable operating region
Stable operating region
EF
F
E
CT
IV
E
S
E
RI
ES
R
E
SI
ST
ANC
E
:ESR
[Ω
]
EF
F
E
CT
IV
E
S
E
RI
ES
R
E
SI
ST
ANC
E
:ESR
[Ω
]
GND
N
P
N
P+
Parasitic element
or transistor
(Pin B)
B
E
Transistor (NPN)
N
P
N
GND
O
(Pin A)
GND
N
P+
Resistor
Parasitic element
P
N
P
P+
N
(Pin A)
Parasitic element
or transistor
(Pin B)
GND
C
B
E
Parasitic element
GND
Fig. 36:Bypass diode
OUT
Vcc
CTL
GND
Reverse current